Assuming your way to do this question is correct.
Similarly, for the question (in part b) \(\lim_{x \rightarrow 0^{-}} f(x^3-x)\)
\[x^3-x>0\]So, as \(x \rightarrow 0^+\), \(x^3-x \rightarrow 0^{+}\). And it is A. Hmmm...